The Society of Automotive Engineers (SAE) has defined multiple levels of autonomous vehicle operation. At levels 0-2, a human driver monitors or controls the majority of the driving tasks, often with no help from the vehicle. For example, at level 0 (“no automation”), a human driver is responsible for all vehicle operations. At level 1 (“driver assistance”), the vehicle sometimes assists with steering, acceleration, or braking, but the driver is still responsible for the vast majority of the vehicle control. At level 2 (“partial automation”), the vehicle can control steering, acceleration, and braking under certain circumstances without human interaction. At levels 3-5, the vehicle assumes more driving-related tasks. At level 3 (“conditional automation”), the vehicle can handle steering, acceleration, and braking under certain circumstances, as well as monitoring of the driving environment. Level 3 requires the driver to intervene occasionally, however. At level 4 (“high automation”), the vehicle can handle the same tasks as at level 3 but without relying on the driver to intervene in certain driving modes. At level 5 (“full automation”), the vehicle can handle almost all tasks without any driver intervention.
An electronic vehicle stability control system in a vehicle is designed to reduce loss of traction by road wheels of the vehicle. A controller responsible for the electronic vehicle stability control receives steering-wheel angle, lateral acceleration, vehicle yaw, and speeds of each road wheel. The controller determines and compares the vehicle's intended direction and actual direction. If the intended and actual direction are different, the vehicle is skidding. The controller then actuates brakes on the road wheels individually to counteract the skidding, such as on an outer front wheel to counteract oversteer or on an inner rear wheel to counteract understeer.